Use TBB task_arena to replace deprecated components

As discussed in #173 (closed)

Probably superseding !1065 (closed)

Deprecated TBB components marked in !982 (merged) are removed. Removing the deprecated tbb::task_scheduler_init causes Gaudi to hang at the thread finalisation barrier in ThreadPoolSvc.

Using tbb::task_arena fixes the endless wait, and also demonstrates a possible migration path from the tbb::task API, since task_area implicitly creates tasks from the functions provided to the enqueue method.

I have copied @ishapova 's conversion of the xxxTask classes from !1067 (merged)

I don't attempt to migrate SerialTaskQueue: !1195 (merged) simply removes it